UNITED NATIONS -?UN Secretary-General Ban Ki-moon on Sunday strongly urged Israel and Palestinian militants "to cooperate with all efforts led by Egypt to reach an immediate cease," saying that "any further escalation will inevitably increase the suffering of the affected civilian populations." ? ?

The secretary-general made the statement after Israel and the Palestinian militants brushed aside the call of the international community for an immediate end to the air strikes on Gaza and the rocket firing into southern Israel by widening Gaza assault and continuous rocket firing against Israeli towns.

"This must stop," Ban said. "I strongly urge the parties to cooperate with all efforts led by Egypt to reach an immediate cease fire."

"Any further escalation will inevitably increase the suffering of the affected civilian populations and must be avoided, " the secretary-general said.

Palestinian rocket fire and Israeli airstrikes continued on Sunday as the Israeli Operation Pillar of Defense entered its fifth day.

On Saturday, Israel broadened its assault on the Gaza Strip from mostly military targets to centers of government infrastructure, obliterating the four-story headquarters of the leading Hamas officials with a barrage of five bombs before dawn, media reports said. ?

Another barrage of rockets was launched from the Gaza Strip to Tel Aviv on Sunday evening, for the second time in 24 hours, the reports said.

Hamas health officials said that 45 Palestinians had been killed and 385 others wounded since Wednesday's escalation in the cross-border battle, the reports said. In Israel, three Israeli civilians have died and 63 have been injured. Four Israeli soldiers were also wounded on Saturday.

"I am deeply saddened by the reported deaths of more than ten members of the Dalu family, including women and children, and additional Palestinian civilians killed as a result of the ongoing violence in the Gaza strip," Ban said in a statement issued here.

"I am also alarmed by the continuing firing of rockets against Israeli towns, which has killed several Israeli civilians, " the secretary-general said. ?

"I am heading to the region to appeal personally for ending the violence and contribute to ongoing efforts to that end," Ban said.

Operation Pillar of Defense comes almost four years after Israel launched Operation Cast Lead, which also aimed to stop Palestinian groups from targeting cities and communities in southern Israel.

Parallel to the fighting, diplomatic efforts are being undertaken mainly by Egypt, along with UN and the United States, to negotiate a ceasefire between the two sides.

According to the Israeli news site Ynet, Israeli Prime Minister Benjamin Netanyahu has promised US President Barack Obama that Israel won't initiate a ground operation unless Hamas escalated its rocket fire.

The Israeli government "will give a chance to the opportunity of a ceasefire, but if there is not an agreement with Egyptian, it will order a ground operation tomorrow (Monday) or the day after tomorrow," the reports added.